/Engine/Source/Runtime/GeometryCore/Public/Spatial/PointSetHashTable.h
Find all points within given query distance from query point. Note that in current implementation the distance must be less than the CellSize used in construction, ie at most the directly adjacent neighbours next to the cell containing QueryPt can be searched
true on success
bool FindPointsInBall ( const FVector3d & QueryPt, double QueryRadius, [TArray](API\Runtime\Core\Containers\TArray)< int > & ResultOut )